


Study Time

by MadamMerlise



Category: Undertale (Video Game)
Genre: NSFW, Other, Reader-Insert, just some good ole smut
Language: English
Status: Completed
Published: 2015-10-20
Updated: 2015-10-20
Packaged: 2018-04-27 06:09:49
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,902
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5036842
Author URL: https://archiveofourown.org/users/MadamMerlise/pseuds/MadamMerlise
Summary: <blockquote class="userstuff">
              <p>College was not nearly as simple as you had hoped, especially when you were taking a Physics Course that you barely understood. You never understood how Sans had convinced you this was a good idea...</p>
            </blockquote>





	Study Time

The seconds ticked away on the clock on the wall, the motion of the hands the only interesting thing to you in the room. You probably should be focused on your test, but you were wholly and completely done. You had written it off.

Sure, you had scribbled in the bubbles and wrote out your name on the scan sheet, but you had no clue what you were actually _doing_. In hind sight, maybe you should have taken Sans up on his offer to explain things to you. You had insisted you were doing just fine. After that conversation, you maybe opened your textbook twice before the test; the first, on the day the test date was announced and the second, the morning of said test. You absorbed nothing.

Speaking of Sans, you peered over at the desk beside you to see your skeletal friend was fast asleep. Glancing up at the front desk to make sure the teacher was not thinking you were cheating, you leaned over the aisle to check out his answer sheet. Completely full. What an asshole. He finished so fast that he had time to fall asleep. You scrunched up your face at him even though his eyes were closed.

The timer on the front desk rang violently, making you snap back to attention. The teacher was explaining how to properly turn in the papers onto their desk, but you were not listening. All the bubbles were filled, but you doubted many of them were correct. Honestly, if you had not already used up all your absences, you would not have even shown up to class. At least now that you had turned something in you might have a fighting chance to make a D.

With a heavy sigh, you gathered you belongs and made your way to the front of the room, tossing your paper atop the growing pile of disheveled sheets to the chagrin of your professor. Out in the hall, you felt Sans take up his usual spot beside you, keeping up with your quick stride. You just wanted to get as far away from that classroom as possible.

"Didn't do so great, huh, pal?" Sans asked. You stuck out your tongue at him. It was juvenile, but you could not help it. You were pissed off with yourself and you were not really in the mood to be given the old "I told you so" talk. He could only laugh, pressing a hand to his chest, feigning hurt. "Ouch. Seriously? Ouch. I am stung. I am just, uh, real broken up over here."

You rolled your eyes. The day was over ( _thank god_ ), so you were excited to hop into your car and leave that horrible place. Sans followed you out, giving you a moment to complain about how awful the test was. You confided in him that you doubted you would make a good grade, but prayed the teacher would be forgiving. Your skeleton friend watched as you started to dig in your bag for your car keys. He had parked his bike next to your beat up vehicle as usual so this was routine for the two of you. His brother, Papyrus, had his car on the opposite side of Sans's bike.

The growing frustration only intensified as you worried about whether or not you had lost your keys, too, and that would be just _great_ , wouldn't it? With a grunt, you dumped out the contents of your bag onto the hood of your car. You binder left a new dent and you heard the keys jingle to the cement, just under the car. Damn it. Sans only watched as you got down to try and reach your keys.

"You know, I'm just going to go out on a _limb_ here and say you need some help with your physics work," he said, shaking one of his arms so you knew that he meant "limb" as in an "arm" or a "leg" and goddamn him and his puns, this was serious! He laughed as you groaned, but continued, "Nah, seriously, pal, I'm more than happy to teach you all the stuff I know...and a little bit of the stuff I still don't really get, haha."

He had offered to before, but, in your combined laziness and ill-placed confidence, you blew him off. Now, on your hands and knees in the campus parking lot close, to tears, the suggestion felt like a godsend.

"Would you really?" He nodded.

"Yeah, of course. Tell ya what, buddy? Come over to me and Papyrus's place. We don't have to start studying right away or anything, we could just watch a bad movie or something, but yeah, you should come."

Mulling it over, you weighed your options. Go home, alone and depressed, and wait anxiously for the results of this very important college exam to be sent to your student profile on the campus website... _or_ have some fun with Paps and Sans?

...

Did you really even need to think about it?

\-----

The house was empty when you walked up to it with Sans, no lights on in any of the windows. It was not your first time visiting them, but it felt strange without Papyrus there. Guess he had not gotten back from campus yet.

Sans let you in and you slipped out of your shoes, kicking them in the general vicinity of Papyrus's spare boots lining the wall by the front door. Sans did pretty much the same. He following you into the kitchen as you deposited your bag on the dining room table. With little warning, you plopped down into one of the creaky, old chairs and let your head flop forward onto the table, hitting your forehead. It did not hurt as bad as your inevitable failure at college life...okay, it did kind of sting a little. All the same, the drive over alone in your car following behind Sans's impossibly fast bike had given you the time to get properly down in the dumps about the test.

Leaving you to your dramatic misery, you heard your friend dump his own bag unceremoniously on the floor by your side, patting your back with his free hands.

"Listen, buddy, it's not the end of the world, no need _tibia sad sack of bones_. It's just one test."

His puns were a comfort and his patting had turned to gentle strokes over your shoulderblades, pressing circles into your tense back with his bony palms. You felt yourself melt under his hands. It had been a long time since you had gotten a massage and honestly, Sans was not half bad at giving one. With a deliberate, slow motion, Sans's hand traveled down your spine, making you arch back a little with a quiet noise creeping out of your throat.

"Hhhhnnnmm~" you grumbled appreciatively. "Can we just do this instead?" The words were out of your mouth before you could stop them. Both of you froze.

"Uh-"

You sat up very quickly, a warm blush spreading down your face, the heat wriggling deep into the pit of your stomach. How embarrassing.

"I need to go to the bathroom!" You had practically shouted. Sans's face was also deeply flushed and he barely registered what you had said before you were shoving him out of the way. Bounding out of the kitchen and up the stairs, you flung your body into the bathroom and slammed the door behind you.

Your heart was fluttering. You tried to convince yourself that it was because you had taken those stairs three at a time in your rush to escape, but you knew that that was not the case. For a long time you had known how you felt about your best friend. His jokes had started to make you laugh harder, his words touched you in a way that they had not before, and you found yourself admiring little things about him. His voice, his quiet ways he only showed you, his strong and handsome structure...

You splashed water on yourself. Staring at your bright red face, you were frustrated. You could not be in love with your best friend, okay. How cliche was that? It would ruin everything. It had taken so much to get Sans to share with you all that he had seen, all that he had been through, there was no way you could mess that up because you started to care for him as more than just the goofy guy who sat next to you in class. But, there you were, screwing it up, just because he had put his hands on you.

He had explained everything he could about the various timelines and things and, while it was still hard to understand, you listened. Sans appreciated that much. It was hard to think about how much that sort of life had hurt him so much. You did not want to just be another bad outcome in some random random area of space time.

A gentle knock at the door shook you out of your inner turmoil.

"H-Hey, uh...about what happened...?" Of course, it was Sans. If you could have willed your soul to escape your body at this very moment, you would have been dead and gone already. Ghosts existed, Napstablook in your English class was proof enough, why couldn't you just vanish?

"L-Look, hey! Just...Just forget about it!" you called out. "I'm just...shit, dude, I'm really sorry, that was totally uncool of me to say." The silence was killing you, but it did not take long before Sans spoke up again.

"What if...What if I don't want to forget about it?" For the second time in the space of ten minutes, you were frozen in shock.

"Um." What were you supposed to say? This had never occurred to you. But Sans was starting to talk again, fast and nervous. You could not see him, but you could picture his face clearly. Knowing him, he was probably sweating up a storm, hands fidgeting in his coat pockets.

"Yeah, I, uh...I really don't wanna forget about it. Uh, is that weird? I just...I'll be honest, I can't stop thinking about you as more than a friend, okay?" Unbidden, your feet had carried you closer to the door. He had not heard your movements, instead continuing, "You just have really...uh, helped me, you know? And I don't _just_ like you because of that or anything! I really do like you for a ton of reasons! L-Like...a _skele_ -ton! Heh heh..." He was so nervous, but he was still making puns. You swung the door open, making him jump back in surprise.

Just as you had imagined, Sans was there, sweat rolling down his skull, eyes wide. You found yourself staring at him. You let your eyes trace his form. If it were possible, you would almost say that his blush got even deeper as a result. Before he could say much more than incoherent babbling, you were talking over him.

"I really like you, too...Like-" You paused, waving your hand, trying to come up with a sufficient increment before settling with, "-a LOT." Sans was quiet, trying to absorb all of this.

Stepping out of the doorway, you came closer to him, close enough that you could see the details on the bones of his face. Little scratches, places where he had gotten hurt in the various timelines he had explored. Your hand came up and brushed the corner of his mouth. He was cold to the touch. "I've been afraid to tell you ever since I realized, you know? You have seen so much...too much, if you ask me. I never want to be another scar for you."

God, that had sounded way more sappy than you intended it to, but it was true all the same. Apparently it had registered in some small way as realization was slowly dawning on Sans's face. Damn, you both were so nervous.

As you were speaking though, your fingers had begun to trace his jawbone. You felt little grooves and rough patches here, too. Every inch of him was absolutely fascinating. There was a story to each little nook and cranny and you desperately wanted to read his body with your fingertips. Maybe you would be less terrified if you knew everything there was to know about San's body. Maybe that would help him feel like you understood him a little better, too.

Sans's chest started to heave unevenly, but he closed his eyes and leaned into your touch.

"Yeah...I know. I've been pretty afraid of this myself," he whispered. He brought his own hand up to rest on top of yours. "Although, now...I really, uh, don't care about it as much anymore?" Turning his face, he pressed his mouth to your palm, trying to kiss you there even though he did not have lips. His nuzzling sent a thrill up your back. "It's weird."

"Screw homework," you blurted out. The sudden statement made Sans laugh.

"You're a real charmer, aren't ya, pal?" You could only laugh at yourself, too, a little giddy from it all. "Hmmm, that's good I guess," Sans mumbled, shutting his eyes again, grin growing wide. "Cause I've got a snake you could charm." Sans was peeking at you with one of his eyes, watching you splutter.

"I...! You just...! Sh-Shut up!" you finally groaned, pulling him against you into a tight hug. You had to stop his smug chuckling or else you were going to collapse from embarrassment. This entire day had been an emotional rollercoaster. And, from the look in his eyes, Sans did not plan for the ride to be over just yet.

So close to you, he practically enveloped you with his enormous jacket, arms stretching around your body to hold you there with him. With his head pressed to you, he could probably hear your heart pounding. Sans's energy practically consumed you, letting your inhibitions fall to the wayside.

Returning to their aimless journey, your hands crept up his back before rubbing at the vertebrae of his neck. He shivered, but as you were warming up, he pushed at you a little insistently.

"Listen, I really wanna get a _bone_ in you, too, b-but Papyrus could, uh, come home any minute now, maybe we should just-"

Your mouth against his quieted him. You felt your bodies' curve against each other, trying to get even closer, to squash away any space between you. The kiss was sort of strange, once again due to the lack of lips of your partner, but neither of you seemed to mind it. With stumbling steps, refusing to be too far apart, you tried to make your way to some privacy.

Somehow, despite your fuzzy brains (did skeletons have brains?), you had found yourselves in Sans's room. Shutting the door behind you, he pinned your body to the sturdy wood. It was his turn to let his hands wander over you.

You felt his cold fingers rub all over you back, down your sides, brushing over your thighs, before nudging under the fabric of your shirt. He traced circles into your skin, wedging his face under your chin to press mock kisses to your neck. The touches had you panting. Who knew that one day you would find yourself about to fuck a skeleton? The thought was completely out of the blue, making you giggle. Sans pulled away slightly with a smirk.

"What's so funny?" he mumbled against your skin. His hot breath made you tremble and clutch at his back.

"N-Nothing, I'm just...happy."

This time Sans pulled away completely to look at you. His expression was soft. He pressed another kiss to your mouth, soft and chaste this time.

"Yeah? Hmmm, me, too."

Words were needless at this point as you let the moment carry the both of you.

Taking your hand, he led you over to the bed, reluctant to not be touching you in some way. He threw the messy sheets out of the way before sitting down. With a sly look, he patted his lap. You obliged, straddling him. Once again his warm breath tickled at your skin. He had his eyes shut as he touched you, like he, too, wanted to map out your body with his hands. You let him explore, sliding your hands under his coat to push it off his shoulders.

He was a little shy at first, but finally helped you take it off of him. Along with it, you grabbed greedily at his shirt. With his top half completely exposed, you dragged a finger down each of his ribs. Getting restless, Sans decided it was your turn to get some clothes off, too.

He removed all the clothes covering your torso, leaving your flesh completely naked to him. Sans raked his eyes appreciately over every inch. Cheekily, he put his hands flat to your sides, rubbed upwards, and then flicked both your nipples with his thumbs. You were writhing, the texture of his cold bones absolutely driving you crazy. It was when his hands drifted to your waistband that you found the sense to speak up again.

"Please tell me how you're going to fuck me." It was a blunt way to ask, but you were honestly wondering how it all was going to work. You were absolutely past the point of wanting to stop. Sans's eyes darkened, pupils fading away, as a hungry grin took over his features.

Putting his hands under your butt, pausing to give it an appreciative squeeze, he lifted you up as he stood. Who knew he was so strong? You wrapped your arms around his face in surprise. He did not mind though, nuzzling into the soft skin of your bare chest. Sans turned to deposit you haphazardly onto his mattress, tugging off your pants and underwear in one smooth motion. His hands were tight under the bends of your knees as he pulled you towards the end of the bed.

A bright flashing iris illuminated one of his eye sockets and, after a moment, you felt the weight of something press against the most intimate part of you. Looking down between you, you saw that Sans had tugged down his shorts to reveal a blue cock protruding from his body. It gave off a faint glow, the magic in it making it feel warm and heavy, yet ethereal and alien all at once.

Sans pulled your knees up, putting your legs over each of his shoulders, turning to kiss your ankles. Slowly, he leaned down, pushing the tip of himself insistently at your entrance as he folded your body as carefully as he could. With a low grumble, he finally answered.

"Slowly..." The way the word crept out of his throat set your skin tingling with anticipation.

He pushed forward, nudging himself into you, relishing in the tight squeeze of your body around his dick. It was torturous, but you loved it. He was filling you up in just the right way. You were enjoying every pleasurable inch that sank into you, until finally he came to rest with his hips flat against your ass, buried inside of you. The both of you had only just started and you were already trembling.

It took a lot for Sans to keep to his word and keep his thrusts slow. He wanted to enjoy this, to really absorb every little expression on your face and the way your body looked and the way it felt to be inside you like this, but it was difficult. You crooned his name and he responded with a firmer thrust, punctuating it by saying your name in turn.

Sans's motions were relentless. His fingers scrabbled at your hips, finally picking up the pace and pulling you back against him with each push forward. His eyes were trained on your face as he huffed out a soft laugh. For some reason, you felt the urge to chuckle, too. This just felt too good. You were both so happy.

His self-control began to dwindle. Sweat dripped down his face as he grunted and finally let himself go, fucking you hard and fast. His dick felt amazing in you and you could not stand it any longer.

With a shudder, you cried out as you came. Sans watched your body writhe and it proved to be too much for him as well. He choked a little as he slammed into you a few more times before cumming deep inside you. Every pulse of his cock made you tremble. It felt amazing. When it was all over, Sans pulled out slowly, leaving you slick and empty, before the magic dissipated. His arms were shaking, but he had the forethought to get off of you before collapsing. The weight of his bones probably would have winded you.

As your breathing returned to normal, you turned to look at Sans, draping a hand lazily across him. The touch made him open his eyes and look at you as well. It was only a moment before he had pulled you into a firm embrace. It felt awkward at first as you tried to find a comfortable spot, but that seemed to be what you two were about, being a little bit awkward in a tender kind of way. His fingers played with your hair, his other hand rubbing circles into your back again. Your own hands were clutching at him, content to just lay there with him.

Heavy with sleep post-orgasm, you perked up at a sudden thought and could not contain the giggle that burst out of you. Sans opened one eye with mock annoyance, curious at your random outburst. You shook your head.

"Thanks for helping me _study_ ," you chuckled.

\-----

**_F._ **

It was there in bright red marker at the top of your scan sheet. You were white as a ghost during the lecture from you teacher after class, telling you that they expected better from you. They said that you might as well have been bubbling in answers randomly (you had) and that they could not understand why you even bothered showing up to class (you did not know either). Silently, you nodded. That was all you could muster.

You wandered out of the classroom, a shell of your former self. Sans was leaning against the door frame, looking you up and down.

"That bad, huh?" You nodded. He took your hand and walked with you down the hall and out the front door of the college. "Ah shit, I'm sorry, babe."

"Why did I let you convince me to major in physics, Sans?" you groaned as you made your way to your car. Sans went over to the passenger side and plopped down beside you. He watched as you pressed your forehead to the leather of the steering wheel. The leather was hot from the sun, but you did not care...ouch, okay, you did care, that was really hot. Sans spoke up as you rubbed at your face.

"Well, I guess it's, uh, not all bad."

You quirked an eyebrow at him, wondering how on Earth he thought things were not absolutely wretched. He shrugged, a wide grin spreading across his face.

"This just means we need to study some more."

**Author's Note:**

> Did not have internet all day yesterday and all day today until RIGHT before I left for work. Normally, I write YDM in Google Docs so I wasn't even able to work on that with the Internet down. In the meantime, I wrote this oneshot. Hopefully this satiates you while I pump out chapter 6 of YDM tonight.
> 
> This fic was actually based off of an ask on Tumblr an anon sent me about Reader from YDM being a physics major so they would have something in common with Sans. I think they meant something kind of fluffy, but I turned it into smut because that's just what I felt like. It's been awhile so please be forgiving. ;v; Check out my Tumblr where I post announcements and nonsense. Send me asks with whatever you like! http://madammerlise.tumblr.com/


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